Damage Resistance Analysis Of Composite Laminates Subjected To Quasi-Static Indentation

As advanced composite structures are widely used in the aerospace structures, more attention has been paid to the research on the damage problems of composite structures. Damage resistance of laminates is proposed as a standard measurement for evaluating the behavior of laminated composites for that reason. This paper focuses on the experimental and theoretical studies of the damage resistance of composite laminates. Some results are obtained as follows:(1) Analysis has been made on quasi-static indentation tests of composite laminates. The failure mechanisms of composite laminates and important parameters affecting damage resistance have been deduced.(2) The classical lamination theory and the contact theory have been combined to predict the initial delamination force and maximum contact force of quasi-static indentation tests. The comparison between analysis results and test data shows that the method proposed in the paper may be used in preliminary evaluation of the damage resistance.(3) A user subroutine is developed for material constitutive relations based on ABAQUS software. Numerical models are founded based on the user subroutine. Single layer failure criterion and delamination criterion are introduced when the user subroutine is developed. The progressive damage analysis of laminates is carried out by using stiffness degradation technique. Comparison between the test data and numerical results of several laminates subjected to quasi-static indentation indicates that the numerical method proposed in the paper can simulate the damage cumulation process with satisfactory, and the predicted damage resistance fits the test data very well.(4) The dent depth is predicted based on the progressive failure analysis combined with the contact theory. The results indicate that the dent depths are nearly identical for a given contact force under different boundary conditions. The boundary conditions have negligible effect on the dent depth, and it is dependent on the local stiffness of laminates in contact area.